The present invention relates generally to via interconnects or transitions, and more particularly, to via transitions for use as micromachined circuit interconnects and methods for making such via transitions.
Pyramid-shaped vias have heretofore been used to provide for vertical interconnection between coplanar waveguides on opposite surfaces of a micromachined substrate. Such conventional pyramid-shaped vias are etched from the same surface of a substrate. The span of the ground planes of the coplanar waveguide is dictated by the thickness of the substrate and its anisotropic etching property. The ground plane span frequently approaches one-half wavelength at millimeter-wave frequencies, causing excessive RF signal loss due to radiation. The vertical transition or interconnection is generally inductive in nature, aggravating impedance mismatch at elevated frequencies.
Accordingly, it is an objective of the present invention to provide for improved via interconnects or transitions that may be used as micromachined circuit interconnects or transitions and methods for making such via transitions.